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View Full Version : Question Broken vacuum reservoir and low MPG



altitude2k
15-08-2010, 12:31 PM
Hi guys,

Proud new owner of a 2008 A3 8P 2.0 TDI (140). Picked it up Thursday, and yesterday was driving to work and there was a serious lack of power. Good start!

Got to work and called out the complimentary Audi Roadside. The guy turned up and found the lug on the vacuum reservoir that holds the pipe in was missing. Basically the turbo had negative vacuum which explains the lack of power. He phoned up Audi Northampton and ordered the part in which gets fitted Monday morning. In the meantime he did a quick fix by putting an Allen key in the end of the pipe to provide at least some vacuum. Got a LOT more power now!

However, my readout on the dash is giving me an average MPG of around 35-40, which sounds pretty low considering the displays tend to OVER estimate. The fuel needle also seems to be creeping down quite quickly. That was over a drive of 40 miles, 90% of which is dual-carriageway.

Do you think that these are related? Part of the reason I bought this engine was for a decent fuel economy, so if I'm getting (in reality) around 30 MPG, I feel like I've very much been missold the car. Or is that problem likely to cause higher fuel consumption and I'm worrying about nothing?

Any thoughts would be appreciated.

kite
15-08-2010, 12:35 PM
I would check the fuel useage once the car has been fixed.
Brim the tank and make your own calculations

altitude2k
15-08-2010, 02:00 PM
I would check the fuel useage once the car has been fixed.
Brim the tank and make your own calculations

This was my plan. Just wondered if the low MPG could be attributed to the vacuum issue. Maybe not directly causing low MPG but making the ECU think it needs to pump in more fuel?